ABSTRACT Clinical Practice Guidelines (CPGs) are essential to improve health care delivery and patient outcomes, and are increasingly tied to reimbursement. To date, the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system has emerged as the leading prescriptive system for developing CPGs and is widely used both in the US and worldwide. Development of CPGs is the product of group judgment. Surprisingly, and despite the importance of group judgments for issuing guidelines, little work has been done to analyze how the CPG panels make their judgments within or outside GRADE system. Because the GRADE is considered the best prescriptive system for development of CPGs, we hypothesize that the panels' group judgments will accurately reflect a relationship between GRADE key criteria (?cues?) and the strength of recommendations, modified to some extent by other factors known to affect people's decision-making. To address our hypothesis, we will assess the impact of GRADE factors on group judgment process vs. individual panel members according to the lens model (SA#1). We will supplement this analysis with the qualitative evaluation of additional constructs that are not formally included in the GRADE system (SA1b). In SA#2, we will address the role of contextual factors and other factors that may affect the consistency of CPG judgments (e.g., more socially relevant topics, greater diversity of CPG panels, and/or panels with conflict of interest will generate greater discrepancy between individual and group judgments). In total, we will study 14 CPG panels, which will generate about 2,000 practice recommendations. To meet our short-term objectives, we propose an innovative study aiming to explain CPG panel judgments using theoretically sound lens model. Our long-term objective is to improve CPG panel judgments accuracy. By improving understanding of CPG judgment processes, the proposed study will exert sustained impact on the way we develop CPGs. Both public health and healthcare financing depend on reliable, trustworthy CPGs. Therefore, it is of utmost importance to understand group judgment processes that are foundations of the CPG development.